Ubuntu Security Notice 5034-2 - USN-5034-1 fixed a vulnerability in c-ares. This update provides the corresponding update for Ubuntu 16.04 ESM. Philipp Jeitner and Haya Shulman discovered that c-ares incorrectly validated certain hostnames returned by DNS servers. A remote attacker could possibly use this issue to perform Domain Hijacking attacks. Various other issues were also addressed.
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Ubuntu Security Notice USN-5034-2
August 10, 2021
c-ares vulnerability
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A security issue affects these releases of Ubuntu and its derivatives:
- Ubuntu 16.04 ESM
Summary:
c-ares could be made to return wrong domains.
Software Description:
- c-ares: library for asynchronous name resolution
Details:
USN-5034-1 fixed a vulnerability in c-ares. This update provides
the corresponding update for Ubuntu 16.04 ESM.
Original advisory details:
Philipp Jeitner and Haya Shulman discovered that c-ares incorrectly
validated certain hostnames returned by DNS servers. A remote attacker
could possibly use this issue to perform Domain Hijacking attacks.
Update instructions:
The problem can be corrected by updating your system to the following
package versions:
Ubuntu 16.04 ESM:
libc-ares2 1.10.0-3ubuntu0.2+esm1
In general, a standard system update will make all the necessary changes.
References:
https://ubuntu.com/security/notices/USN-5034-2
https://ubuntu.com/security/notices/USN-5034-1
CVE-2021-3672